Method and apparatus for die cutting blanks from stacks of sheet material



United States Patent 1,283,829 11/1918 Loesser Willi A. Schneiderlnventor Adliswil, Switzerland Appl. No. 731,398.

Filed May 23, 1968 Patented Dec. 15, 1.970

Assignee- Frey, Wiederkehr & Cie AG,

Briefumschlag und Papierwarenfabrik Zurich, Switzerland a joint stockcompany of Sweden.

Priority May 29, 1967 Germany No. 1,561,442

METHOD AND APPARATUS FOR DIE CUTTING BLANKS FROM STACKS 0F SHEETMATERIAL 19 Claims, 13 Drawing Figs.

1 Int. Cl. 826d 7/02,

Field ofSearch 83/27, 34, 36, 50, 55, 104, 112, 123,126, 153, 206, 409,412, 561, 648, 160

References Cited UNITED STATES PATENTS 1,986,983 1/1935 Sime 83/409X2,391,304 12/1945 Fink 83/104 3,033,067 5/1962 Thumin 83/206 3,081,6553/1963 l-liroumietal. 83/112 3,306,145 2/1967 Edwards 83/206X 3,460,4158/1969 Philipp 83/27 FOREIGN PATENTS 278,882 10/1914 Germany 83/123Primary Examiner-William S. Lawson Attorney-Fishbum, Gold and LitmanABSTRACT: Stacks of sheet material to be die cut into blanks arepartially suspended from a single clamped edge by multiple spaced apart,individually actuatable, clamps on a tilted stationary table and under astationary but rotatable die. A die backing plate is mounted in thetable for rotation and adjustment and includes a holding element axiallycooperating with a similar element movable within the die for urging theblank stack rearwardly of the die for lateral removal by a graspingtool. The stacks are moved along perpendicular coordinates on the tableand an air cushion is provided to reduce friction. A portion of thetable is pivotable to the horizontal for initially receiving andaligning the stacks and the clamps are adapted to shift and rock torelieve adverse forces during die penetration. Reduced fluid pressure issupplied to the die press cylinder for stop adjustment of the fullpressure die stroke.

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swan 6 OF 8 In van [or WILLI A. SCHNEIDER QCELM ZLMJ {$4M ATTORNEYSPATENTEU DEC] 5 I970 SHEET 7 OF 8 \m A: Q Q 8 A fi a; 222,;5222;;2552222=25; 52:2 5%; 2E: v m Q gs a w a w \x .I f U llfi in MI A 2. g 5 g 3 g Q Q R S 3 g WILLI A. SCHNEIDER ATTORNEYS PATENIEnnEmsmm3545990 sum 8 0F 8 /n ven [0r WILU A. SCHNEIDER BY MM (3M9 ATTORNEYSFROM STACKS OF SHEET MATERIAL V This invention relates to a method'andapparatus for die I cutting blanks and the like from stacks of sheetmaterial, and

more particularly tosuch amethod'and apparatus which utilizes arelatively movable die and stack support for obtaining multiple die cutsfrom a single stack.

Apparatus for die cutting blanks from stacked sheet material are knownto use a stack supporting table adapted to move the stack inonedirection and a .die supporting member adapted to move the die in atransversev direction whereby the entire sheet surface may be coveredfor'multiple die cuts.

Such die supporting members have been adapted to rotate through desiredangles-for more efficientnesting of adjacent cuts. in using such priorart apparatus, the die cut blank stacks commonly remain onthe tablesurrounded by'waste material until the entiresheet'stack-is cut,whereupon the individual blank stacks are removed from the tablemanually.

Such known-apparatus presents several difficulties. Because the die isplaced successively.into different positions relative to thetable, thelatter must becovered on the entire die cutting edge contacting surfacewith a relatively soft backing layer or plate of 'crosscut orendfgrained wood or like material. Thedistributionof small grooves or.notches in the backing plate caused by repeated'contact with the diecutting edge produces a-rough, high friction surface, rendering itextraordinarily difficult to move the sheet 'stackover the backing platefor alignment against stops and c la'rnp the stack into proper positionwith known clamping=devices.' Also, any subsequent jarring or jolting ofthe table under these conditions tends to again produce a shifting ofaligned sheets which is difficult to correct.

A further problem with known apparatus is the tendency to produce abuckle withinthe stack upon die penetration. This is caused by theconical'or wedge-shapeddie walls operating in conjunction with tightclamps on multiple edges of the stack, and is aggravated by theroughsi-irface on the backing plate and retention of cut blanks withinthewaste material.

A still further difficulty experienced with known die cutting apparatus,and particularly in the vicinity of tight stack clamps, is the lack ofaxial die penetration through the stack,

whereupon the blanks formed from the upperpart of the stack deviate fromblanks formed therebelow. This may produce serious register problems,especially with previously printed sheets. Also, upondie cutting closelyadjacentto theclamps, the resulting forces often lead to diebreakag'e:

table bearing surface to float the stack on a thin air cushion. Byrotatably mountinga suitable die backing plate in the support table,and, depending upon the die shapes, displaced eccentrically from the dieaxis, the die does not seat repeatedly at exactly the same locationwhereby the useful life of the backing plate is extended. Such a backingplate also lends itself to convenient height adjustment to compensatefor wear and'pen'nit ultimate replacement without involving the majorportion of the support table.

A further feature of this invention, is that no table stops for sheetalignment are provided in the conventional sense, but rather, the stackis supplied to the tablealready aligned and held tight along one of itslongitudinal edges while being fed through movement in two directions"with respect to the stationary die.

A still further feature of this invention is the provision for .graspingthe cut blank stack within the hollow die between a the die, whilegrasped, and subsequently moved sideways from a position rearwardly ofthe die through a lateral aperture by means of a pliers shaped tool uponrelease of the holding elements. Thus, the blank stack is removed aftereach die penetration without the need for moving the die from itsoperational axis. Also, this permits the die stroke to be limited to alength only slightly greater than the sheet stack thickness whichprovides advantages in apparatus construction and operation.

An additional important feature of this invention is the provision of aunique clamp structure for the sheet stack which is adapted to shift andalso rock or pivot about an axis extending longitudinally of the clampedstack edge under the forces produced by the penetrating die. .Thus, inview of the and/or exert damaging pressures on the-die,;while permittingIt has been recommended to decrease the forces resulting from diepenetrationby reducing the resistance of the sheets which stretcharound'the die through the use of crosscutters disposed on the outerside of the die wall. This relieves the tension which would otherwisebuild up in-th'e waste material surrounding the blanks, but often is notsatisfactory because the crosscutters tend to reach partially into thematerial provided for subsequent die cuts, thus interfering with theeconomical utilization of the sheet material.

It is the principal object of this inventionto overcome theaforementioned difficulties while providing almethod and apparatus welladapted for the high speed automatic production of high quality blanks.

In the practice of this invention, thev t ack-of sheet material to bedie cut is clamped on only one longitudinal edge and is moved partiallyinto suspension in an inclined plane, such as 45 from the horizontal,onto a stationary, inclined support table under a correspondinglyinclined stationary die, the.

the stack to be easily realigned following the cut. Also, the use ofmultiple individually controlled and withdrawable clamps permits diecutting adjacent the clamped edge without release thereof.

For convenience in initially depositing and aligning the sheet stack,structure is provided for pivoting a receiving portion of the supporttable outof an inclined. operational position to a horizontal stockreceiving position.

- As a still further feature of this invention, the adjustment of thedie stroke is facilitated by arrangin'g to supply the die press cylinderwith a fraction of its nonnal operating fluid pressure, for example,l/30thereof, whereby the die may be bottomed against its backing platewithout damage for accurately setting the stroke stop used underoperating conditions. This pressure reduction is also desirable'as asafety feature during other nonproduction use of the apparatus. I

The above features render die cutting apparatus embodying this inventionparticularly well adapted forautomatic remote clamped and partiallysuspended stack being moved in the inclined plane along twoperpendicular coordinates. This results in the die always seating atsubstantially. the same place with respect to the support table, wherebythe stack bearing surface of the table, except at the limited'diecontacting area,

remains undamaged by the die c'utting'edge, permitting the 1 controlthrough a programmed coordinating device such as a suitable operationalcomputer receiving instructions from punched card programs or the like.

Other objects and advantages of this invention will become apparent fromthe following description taken in connection with the accompanyingdrawings wherein are set forth by way trating a stack of sheet materialclamped on the inclined table friction resistance of the overalltable-bearing surface to be held as low as possible. Such a constructionconveniently per-- mits the table bearing surface friction resistance tobefurther reduced through the formation of air discharge ports at thefor die cutting. a

' FIG. 2 is a diagrammatic, fragmentary view related to FIG.

, 1 illustrating the cut blank stack displaced normally from the I planeofthe sheet stack into alignmentwith a lateral removing tool.

FIGS. 3 too inclusiveare sequential diagrammatic fragmentarycross-sectional views illustrating the displacement of a stack edgeduring die penetration and subsequent realignment.

FIG. 7 is a somewhat fragmentary side elevation of the apparatus showinga blank stack in position behind the die for lateral removal.

FIG. 8 is a cross-sectional detail view through the apparatusparticularly showing the sheet stack support table including the diebacking plate.

FIG. 9 is a cross-sectional detail view through the apparatusparticularly showing the die support and press cylinder arrangement.

FIG. 10 is a plan detail view of the apparatus taken generally on theline X-X, FIG. 7, particularly showing the sheet stack support table andedge clamps.

FIG. 11 is a cross-sectional detail view taken on the line XI-XI, FIG.10, on an enlarged scale particularly showing details of an edge clamp.

FIG. 12 is a cross-sectional detail view on a further enlarged scaleshowing a portion of an edge clamp.

FIG. 13 is a plan detail view taken on the line XIII-XIII, FIG. 11,showing further portions of an edge clamp.

Referring to the drawings in more detail:

With reference to FIGS. 1 and 2, a sheet stack B is shown lying on aninclined support table A where it is held tightly by its upperlongitudinal edge with pivotable edge clamps C, the structure beingadapted through means described below to feed the stack B to astationary die assembly D which is aligned with a die backing plate Eforming part of the support table A. The table A includes a portionmounted for horizontal motion on guide rails F and carrying the'edgeclamps C for movement in the plane of the die backing plate Eperpendicularly to the direction of movement on the guide rails F. Thereis disposed within the die assembly D a holding element or press pad G,and opposite thereto in the die backing plate E an additional holdingelement H is arranged whereby the two elements cooperate in grasping thestamped out blank stack therebetween and moving same normally out of thesurrounding sheet stack B into a position rearwardly beyond the diewhere a pliers shaped tool .I may grasp the blank stack upon release ofthe elements H and G for withdrawal laterally.

With reference to FIGS. 3 to 6, the sheet stack B is tightly securedalong one longitudinal edge by means of the pivotable edge clamps C insuch a manner, described further below, that the individual sheets mayslightly move orslide with respect to each other in response to forcescreated by penetration of the die wall in the die assembly D. After thedie is withdrawn from the sheet stack B the displaced sheets may bebrought back into overlying alignment through a suitable pressure meansK which engage the longitudinal edge of the material B still held tightby means of the clamps C.

Referring particularly to FIGS. 7 to 10, the illustrated example ofapparatus embodying this invention includes a bed 11 having an uprightbrace or arm 12 on which an hydraulic press cylinder assembly 13 ismounted inclined 45 and having therein a piston rod assembly 14. Arotatable die assembly 15, described below, is carried by the piston rodassembly 14 and supports a hollow, blank cutting die 16. A circular diebacking plate 17 is mounted opposite the cylinder assembly 13 in aninclined plane perpendicular or normal to the cylinder assembly axis.The plate 17 lies in the same plane and forms part of a sheet stacksupport table 18.

A portion of the support. table 18 is pivotally mounted on a carriage 19whereby'it is displaceable horizontally along the bed 11 as well aspivotable from a tilted or inclined position to the horizontal, as willbe explained in more detail below. A clamping assembly 20 is slidable onthe table 18 transversely to the'direction of movement of the carriage19 and includes edge clamps 21 adapted to' grasp an edge of a sheetstack 22, thus making it possible to move each point of the stack 22over the backing plate 17 and under the die 16.

A press pad or holding element 23 is mounted for axial movement withinthe'piston rod assembly 14 and a holding element24 is disposed inaligned relation to the element 23 in the backing plate 17. The elements23 and 24 are effective, in

a manner described below, together with a pliers shaped tool 25 toremove the cut blank stack from the die 16 and convey same laterally ofthe die stroke axis after each cutting cycle.

Referring more particularly to the cylinder assembly 13, a base member26 forming a part thereof is fixed on the bed arm 12 and receives acylinder 27 therein. The conventional packings and known cooperatingstructure related to the cylinder assembly 13 are not shown. Within thecylinder 27 the piston rod assembly 14 is secured against rotation andcomprises a piston rod 28 with a piston 29 located intermediate the endsthereof. A flange 30 is fixed on the lower end of the piston rod 28 anda mating flange 31 is rotatably mounted thereagainst by means of a pin32 journaled within the piston rod 28 and secured longitudinallythereof. 0n the upper end of the piston rod 28 a thread is providedadjustably receiving a stop nut 33 which is adapted to engage a stopring 34 secured on the cylinder 27 for limiting the downward stroke ofthe piston rod. The stop nut 33 is secured, in this example, in adjustedposition by means of a lock screw 35, however, it is to be understoodthat for remote control purposes, the stop nut 35 may be unlocked,rotated and relocked by any suitable remote control means. The cylinder27 is connected through suitable hose lines 36 and 37 to control valveand hydraulic pump means (not shown) in a conventional manner. Therotatable flange 31 has gear teeth 38 on the periphery thereof andengaged with a pinion 39 fixed to the shaft of an hydraulic motor 40secured to the fixed flange 30. The hydraulic motor 40 is connectedthrough suitable hose lines 41, 42 with control valve and hydraulic pumpmeans (not shown) in a conventional manner.

The die assembly 15 is fixed to the underside of the rotatable flange 31and comprises a box-shaped body having an upper part 43 secured to theflange 31 and a lower part 44 carrying a plate 45 fixed to the die 16.The plate 45 is removably received in the die assembly through insertionagainst edge retainers 46. The die assembly 15 includes a wall 47provided with a lateral aperture 48 through which the pliers-shaped tool25 is inserted and withdrawn for laterally removing the cut blank stack.

A cylinder 49 is disposed axially within the rotatable flange 31 andpiston rod assembly 14 and receives therein a piston rod and piston 50carrying the holding element or press pad 23 for longitudinal relativemovement with respect to the surrounding piston rod 28. The cylinder 49is connected to a source of compressed air below the piston 50 through ahose line 51, bore passageway 52 extending into the fixed flange 30,annular groove 53 in the movable flange 31 and bore passageway 54in theflange 31. A hose line 55 associated with the end cap 56 carrieshydraulic fluid to the upper side of the piston 50.

The die backing plate 17 comprises a circular disc 61 supporting anupwardly projecting ring 62 surrounding a plate 63 made of crosscut orend-grained wood or the like. The disc 61 together with the last-namedring and plate are rotatable on a bushing 64 positioned eccentrically tothe axis of the piston rod assembly 14. Positive rotation of the plate63 may be accomplished through peripheral gear teeth 65 engaged withsuitable driving apparatus (not shown). The disc 61 is mounted on sixelongated rods or'screws 66 which are adjustable through a supportingplate 67 by means of sprocket wheels 68 engaged with roller chains 69.The supporting plate 67 is fixed on the machine bed 11 and, throughmovementof the roller chain 69 by suitable means (not shown), the plate63 is adjustable in height. Referring particularly to FIG. 10, the fixedcarrier plates 57, 58 and 59, forming pan of the support table 18, liein the plane of the upper surface of the plate 63.

A cylinder 70 is disposed in and below the supporting plate 67,concentrically with the piston rod assembly 14, and movably supports apiston rod and piston 71 therein for longitudinal movement. A contactmember 72 forming part of the holding element 24, is rotatably mountedin the last-named piston rod at the end facing the holding element orpress pad 23. The cylinder 70 is connected through a hose line 73 with asource of compressed air exposed to the upper side of the piston 71 andthrough a hose line 74, extending through the cylinder end cap 75, witha source of hydraulic fluid exposed to the lower side of the piston 74.Because the diameter of the piston 71 is greater than the piston 50 ofthe press pad 23, with equal'fluid pressures the force exerted by thepiston 71 may overcomeand slide back the press pad 23. The upper side ofthe piston 71 is constantly exposed to compressed air through the hoseline 73 to provide a return stroke. It is noted that, in the case ofrelatively long and narrow blanks, compressed air may be suitablyintroduced between the lowennost blank and the plate 63 within ihe die16 in order to help support and urge'the rearward travel or discharge ofthe blank stack through the die along with the holding element 24.

The carriage 19 includes a plate 86 mounting four bolts or pins 76rotatably carrying rollers 77 which are received and guided in rails 78fixed to the machine bed'l'l. The piston rod 79, of an hydrauliccylinder 80 engaged with the machine bed 11, is secured to a bolt or pin81 mounted on the plate 86 whereby the carriage 19 may be di'splacedaasdesired in a horizontal direction. T t

A portion of the sheet stack support table 18 is connected, by means ofa hinge pin 82, with the carriage 19 and an hydraulic cylinder assembly85 is disposed between an anchor pin 83 mounted on the plate 86 and apin 84 mounted on the pivotal portion of the support tableISsTheoperation of the hydraulic cylinder assembly 85 causes the hingedportion of the support table l8-to shift between an operating positioninclined 45 and a horizontal position for-deposit of the sheet stack 22thereon. P I, v

A plurality of apertures 60 are providedin the support table 18 throughthe pivotal portion as well as the stationary carrier plates 57, 58 and59. Suitable means (not shown) are provided for introducing compressedair through the apertures 60 so as to form a thin blanket beneath asheet stack 22 permitting it to slide on the support table surface withlittle resistance.

Referring particularly to FIGS. and 11, the clamping assembly includes acarriage 89 guided in a slot 88 in the tilting portion of the supporttable 18, the carriage 89 being maintained in sliding position by meansof cover plates 90. A threaded spindle 91 is rotatably mounted below thecarriage '89 and secured against longitudinal displacement. The spindle91 engages a nut 92 fixed to the carriage 89 whereby the rotation of thespindle serves to displace the carriage 89 transversely to the directionof movement offthe carriage 19 on the rails 78. The spindle 91 is drivenby means of a suitable hydraulic motor'87 coupled therewithi In thisexample, four of the edge clamps Zl are secured on the carriage 89through anchor boltsgextendi'ng within a keyslot 93. Referring to FIGS.11, 12 and 13, the edge clamps 21 respectively consist of a base member,94 having a front wall 95 and two sidewalls 96 each having a somewhatrectangular therefrom through the end walls of the cylinder 99. A sourceof compressed air is connected to the cylinder 99 through suitable hoselines 103 and 104. A slottedpiece 105 is connected to the end of thepiston rod 102 and has guide edges 106 and 107 so formed that a bolt orpin'108 is held in the position shown in FIG. 11 when air under pressureis introduced through the hose line 104. t 5

Referring to FIG. 13, a lower clamping jaw 109 is secured between twodouble arm levers 110'and an upper clamping jaw 111 is, secured betweentwo double arm levers 112, the levers 110 and 112 being rotatablyjournaled on the pin 108 and held laterally by means of sphericalwashers 113 and 6. A compressed air cylinder 115 is pivotally connectedlower hose line 122 causes the" clamping jaws to move away from oneanother.

At the right-hand end of the piston rod 101, as seen in FIG.

11, there is disposed a stop member 123, corresponding to the pressuremeans K discussed above with respect to FIGS. 3-6, for engagement withthe clamped edge of the sheet stack 22.

In operating the edge clamps 21, three conditions are utilized asfollows: (a) the edge of the stack sheet is clamped between the jaws 109and 111 by the introduction of fluid under pressure through the hoseline l22'while fluid pressure is maintained in the hose line 104 wherebythe stop member 123 provides a guide for lining up the sheet stack edgeduring clamping; (b) when the pressure is relieved from the air cylinder99, the pin 108 is free to slide downwardly along the front wall 98 ofthe opening 97 whereby the slotted piece together with the piston rods101 and 102 move to the left thus shifting the stop member 123 to theleft and away from the stack edge. During this occurrence the clampingstructure is designed to tilt downwardly about apoint at the lower edgeof the clamped stack edge. Further, the clamp is free to shiftrearwardly until the pin 108 abutsthe rear edge or wall of the opening97. The introduction of air under pressure through the hose line 104will automatically readjust the proper positions of the clamping jawsand stop member with respect to the table 18 at the beginning of eachcut, thus repositioning the stack and realigning the clamped edge, FIG.6; (0) when it is desired to cut close to one of the edge clamps 21,that particular clamp may be selectively released through operation ofthe air cylinder 115 and withdrawn rearwardly through the introductionof compressed air through the hose line 103, whereby the stop member 123and clamping jaws are shifted to the left as viewed in FIG. 11. Theremaining edge clamps continue to hold during die cutting adjacent thewithdrawn clamp. For regrasping the stack edge with the withdrawn clamp,suitable grooves (not shown) may be placed in the table surface or theclamping jaws suitably shaped for replacing beyond the stack edge.

Referring particularly to FIGS. 9 and 10, the pliers-shaped tool 25 isshown in position for laterally removing the stacks of blanks liftedfrom the plane of the stack 22 and held between the press pad 23 and theholding element 24. The pliersshaped tool 25 comprises tongs in the formof a fixed jaw 124 and a movable jaw 125 mounted on a rod 126 which isaxially slidable in a bearing member 127. The jaws 124 and 125 arethereby movably disposed between an upper position for the reception ofthe blank stack therebetween and a lower position spaced laterally ofthe die assembly 15. The operating v cycle of the tool 25 may be startedwhen the press pad 23 with piston rods 101 and 102 extending in oppositedirections achieves its rest position as shown in FIG. 9, this conditionbeing sensed, for example, by a limit switch (not shown). In

handling very thin or soft blanks, itmay be desirable to in clude asheet of relatively stiff cardboard on the upper and lower surfaces ofthe sheet stack.

For the automatic control of the above-described apparatus, suitablesolenoid valves (not shown) are disposed in all of the hydraulic andcompressed air hose lines to be actuated by suitable control equipment(not shown), in conjunction with limit switches and the like (notshown), such control equipment preferably taking the form of a digitalcomputer adapted to receive a perforated card program.

The pressure applied to the piston 29 for the die cutting stroke issuitably adapted to be quickly variable from normal cutting pressure,for example 200 atmospheres, to a relatively low pressure, for exampleabout 6 atmospheres. With this arrangement, the die may be bottomed ontothe surface of the uncovered die backing plate 17 for proper adjustmentof the stroke, without damage to the die or plate, substantiallyfacilitating the adjustment. The reversion to low pressure may beadvantageously accomplished also during other periods of nonproduction,for example during program change, apparatus malfunction or any otherintentional or unintentional interruption of production.

In operation, the sheet stack 22 is placed upon the pivoting portion ofthe table 18 while it is tilted into a horizontal plane with the clampcarriage 89 withdrawn toward the hydraulic motor 87. The sheet stack isaligned and clamped with the edge clamps 21 in the manner noted above at(a). The initial alignment and clamping, as well as subsequentoperations, are facilitated by the introduction of air through theapertures 60, reducing friction between waste sheet stack and thesupport table. The pivoting portion of the sheet stack support table isthen tilted into the plane of the stationary portion including thecarrier plates 57, 58 and 59 and the hydraulic motor 87 and carriagecylinder 80 are operated to successively position the sheet stackbeneath the withdrawn die 16 in accordance with a previously designedprogram to obtain the maximum number of blanks from the sheet stack.Between each stroke of the die, the die assembly 15 may be rotated bythe hydraulic motor 40 to properly position the die angularly forminimum waste and, as noted above at (c), the respective edge clamps 21may be individually withdrawn to permit die cutting adjacent the clampedstack edge. During penetration of the die the clamping assembly 20 maybe released as noted above at (b) permitting displacement of the clampededge as shown in FIG. 4, thereby reducing lateral forces within thestack which may otherwise cause poor quality blanks or damage the die.During penetration of the die, the press pad 23 is urged against thestack and upon completion of the cutting stroke the holding element 24is urged axially toward the press pad 23 with greater force, thus urgingthe blank stack rearwardly out of the die and into the hollow interiorof the die assembly 15 where the tool 25 enters and withdraws the blankstack through the lateral aperture 48 upon release of the holdingelement 24.

Although certain specific methods and structures embodying thisinvention have been illustrated and described, it is not to be limitedthereto except insofar as such limitations are included in the followingclaims:

lclaim: 1. The method of die cutting blanks from a stack of sheets andthe like comprising the steps of:

a. clamping said stack along an edge;

b. partially suspending said stack by said edge in an inclined plane onan inclined support; and

c. pressing a die through said stack in a direction normal to 'I saidinclined plane.

2. The method as set forth in claim 1 including the step of: conveyingsaid partially suspended stack along two coordinates in said plane forpositioning said stack with respect to said die.

3. The method as set forth in claim 1 including the step of: rotatingsaid die about an axis nonnal to said inclined plane prior to pressingthrough said stack.

' 4. The method as set forth in claim 1 including the step of: releasingsaid clamped edge for tilting in response to the penetration of said dieinto said stack.

5. The method as set forth in claim 1 wherein:

a. said edge is clamped at spaced apart locations therealong; andincluding the step of b. selectively releasing said clamped edge at alocation adjacent die penetration into said stack.

6. The method of die cutting blanks from a stack of sheets and the likeas set forth in claim 1 wherein said die is hollow and receivableagainst a die backing plate and including the steps of:

.a. axially grasping the cut blank stack within the die;

b. moving the axially grasped blank stack rearwardly through the die;

c. laterally grasping the blank stack in a location rearwardly of thedie;

edge clamping means; and

c. said movable portion being adapted for movement along said stationaryportion to position a clamped inclined sheet stack over said die backingplate. 8. The apparatus as set forth in claim-7 wherein: said movableportion is adapted for tilting from a horizontal position for receivingthe sheet stack to the inclined attitude.

9. The apparatus as set forth in claim 7 wherein: said movable portionstack edge clamping means is adapted for movement in a directiontransverse to the direction of movement of said movable portion alongsaid stationary portion.

10. The apparatus as set forth in claim 7 wherein: said die plungingassembly is adapted to rotate a cutting die in a plane parallel to theinclined plane of said stationary portion.

11. The apparatus as set forth in claim 7 wherein: said stationary andmovable portions are in the same plane inclined approximately 45 withrespect to the horizontal.

12. The apparatus as set forth in claim 7 including: mounting structurebetween said die backing plate and said stationary portion adapted topermit rotation of said plate about an axis parallel to the die stroke.

13. The apparatus as set forth in claim 12 wherein: said mountingstructure includes means for adjusting the height of said die backingplate with respect to the stationary portion of said support table.

14. The apparatus as set forth in claim 7 wherein: air dischargeapertures are located in said sheet stack supporting table for floatingthe sheet stack on a thin cushion of air.

15. Apparatus as set forth in claim 7 wherein said die assembly includesa hollow die movable against said die backing plate comprising:

a. a first holding element adapted for axial relative movement withinsaid die from a rest position behind said die; and b. a second holdingelement associated with said die backing plate and axially movablyaligned with said first holding element, said second holding elementbeing adapted to cooperate with said first holding element for graspinga cut blank stack therebetween within said die and urging said blankstack from within said die to a position rearwardly of said die.

16. The apparatus as set forth in claim 15 including: lateral graspingmeans associated with said apparatus and adapted to grasp said blankstack at said position rearwardly of said die and remove said blankstack laterally thereof upon release of said blank stack by said holdingelements.

17. The apparatus as set forth in claim 7 wherein said edge clampingmeans includes:

a. a base member;

b. an edge clamp including a pair of lever arms each having a clampingjaw at one end thereof;

c. a transverse pin pivotally connecting said arms at positions spacedfrom said jaws for pivotal movement of said jaws toward and away fromeach other, force producing means engaging said lever arms forselectively producing said pivotal movement;

d. said base member having a receiving and retaining portion therein forsaid pin, said receiving and retaining portion being of substantiallygreater size than said pin permitting said clamping jaws to shift androck in the plane of pivotingot 55m leverar ms but independently of saidlever arm pivoting; and

e. a draw member movable with respect to said base member and engagingsaid pin, saiddrawmember being adapted to selectively draw said pin intotight engagement with said receiving and retaining portion whereby saidclamping jaws are placed into a predetermined position for initialclamping of said sheet stackedg'e. 18. The apparatus as set forth inclaim 17 including: a stack

